Imaging apparatus and method, recording medium, and program

ABSTRACT

An image capturing apparatus includes: a focal position adjusting device operable to adjust a focal position of an optical system to a predetermined position in a first image capture period and change the focal position of the optical system in a second image capture period; a display operable to display an image captured in the first image capture period; a distribution generator operable to generate a distribution of sharpness corresponding to focal positions based on an image captured in the second image capture period; and a focused position detector operable to detect the focal position of the optical system, at which an image of a subject is in focus, based on the generated distribution of sharpness.

CROSS REFERENCES TO RELATED APPLICATIONS

The present invention contains subject matter related to Japanese PatentApplication JP 2004-094791 filed in the Japanese Patent Office on Mar.29, 2004, the entire contents of which being incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an imaging apparatus and method, arecording medium and a program, and more particularly relates to animaging apparatus and method, a recording medium and a program, whichare capable of focusing at any subject positioned inside an imagingfield by enabling selection of a focused position.

2. Description of Related Art

An imaging apparatus having an automatic focusing mechanism, which isreferred to as an auto-focus, is well-known to public.

The automatic focusing mechanism performs focusing operation to achievea focus state by analyzing high frequency component of a signal for acaptured image, detecting sharpness of the captured image, andcontrolling a position of a focus lens such that the high frequencycomponent becomes maximum or local maximum. In other words, theautomatic focusing mechanism controls the focusing at a subject image byusing property such that the high frequency component in the imagesignal is increased since the image signal changes sharply at an edge ofthe subject image if the subject is in focus, and by adjusting positionsof optical parts such as the focus lens and the like so that the highfrequency component becomes maximum.

Further, Japanese Patent Publication JP 07-74856 discloses an automaticfocus arranging method. In this method, an objective lens or a sample ismoved from a sufficiently near focus point to a sufficiently remotefocus point for capturing a still image while storing a position of themaximum contrast obtained within a range of this movement, and thefocusing is performed by adjusting a distance between an subject and theobjective lens in such a way that the contrast of the subject imagebecomes the maximum.

SUMMARY OF THE INVENTION

However, if the foregoing method is applied to capture a moving image,an image taken in the middle of operation for detecting the focusedposition may be displayed, thereby resulting an unsatisfactory orincomplete image.

Further, if a plurality of subjects exist inside the imaging field,there is a disadvantage such that one of the subjects which is notintended by a user is brought into focus. In such a case where theplurality of subjects can be brought into focus respectively, the usermay be required to decide which one of the subjects is brought intofocus. However, in order to enable the selection of the subject to befocused, the automatic focusing system may need to detect positions of alens for focusing by actually moving the lens since sharpness of animage to be captured has to be detected in this system. However, if animage is captured while the lens position is being moved, an imageduring such a focused position detecting operation, in which no subjectis brought into focus, is outputted or recorded, so there was adisadvantage that the user is prevented from obtaining only focusedimages.

Another method is devised to alleviate the above-described disadvantage.In the method, in order to select or change a target subject to bebrought into focus without changing an imaging field, sharpnessdetection regions are displayed on a display for selection. Further, oneof the regions on an image is selected by using a touch panel inputmechanism, a line-of-sight input mechanism or the like, for specifying aposition to be focused. However, in this method, when a plurality ofsubjects that may serve as potential focused positions in the imagingfield are taken to be superimposed, it is difficult to select individualsubject even if one of the sharpness detection region is specified byusing the touch panel input mechanism, the line-of-sight input mechanismor the like, so there was a disadvantage that the user is prevented fromfinishing specifying an accurate position to be focused.

Accordingly, it is desirable to be able to properly focus at anarbitrary subject while detecting a focused position without making adisplayed image illegible or incomplete even if there are a plurality ofsubjects within an imaging field, which may serve as a plurality offocused positions. The present invention is made in view of thesituation described above.

An image capturing apparatus according to an embodiment of the presentinvention may include: focal position adjusting means for adjusting afocal position of an optical system to a predetermined position in afirst image capture period and adjusting so as to change the focalposition of the optical system in a second image capture period;displaying means for displaying an image captured in the first imagecapture period; distribution generating means for generating adistribution of sharpness corresponding to focal positions based on animage captured in the second image capture period; and focused positiondetecting means for detecting a focal position of the optical system, atwhich an image of a subject is in focus, based on the distribution ofsharpness corresponding to the focal positions generated by thedistribution generating means.

The first image capture period and the second image capture period maybe alternately repeated.

The focal position adjusting means may be arranged in such a way thatthe focal position of the optical system is adjusted by moving theposition of a focus lens.

The focal position adjusting means may be arranged in such a way thatthe focal position of the optical system relative to an image capturingdevice is adjusted by moving the position of the image capturing device.

The focal position adjusting means may be arranged in such a way thatthe focal position of the optical system relative to an image capturingdevice is adjusted by changing a form of the optical system.

In the second image capture period, the focal position adjusting meansmay be arranged such that the focal position is adjusted by moving theposition of the focus lens with non-equal intervals.

The image capturing apparatus may further include focused positiondisplay image generating means for generating a focused position displayimage that indicates focused positions detected by the focused positiondetecting means.

The image capturing apparatus may further include image composing meansfor combining the focused position display image generated by thefocused position display image generating means and the image capturedin the first image capture period. Further, the display means may beadapted to display the image captured in the first image capture periodthat is combined with the focused position display image.

The image capturing apparatus may further include selecting means forselecting a focused position from the focused position display imagegenerated by the focused position display image generating means. Thefocal position adjusting means may be arranged such that the focalposition of the image captured in the first image capture period isadjusted to a focal position corresponding to the focused positionselected by the selecting means.

The image capturing apparatus may further include zoom setting means forcontrolling zoom operation of the optical system. The focal positionadjusting means may be arranged such that the focal position of theoptical system is adjusted to a predetermined position in response tothe zoom status set by the zoom setting means in the first image captureperiod, and recalculate the focused position of the optical systemobtained in the second image capture period in response to the zoomstatus set by the zoom setting means.

An image capturing method according to an embodiment of the presentinvention includes the steps of: adjusting a focal position of anoptical system to a predetermined position in a first image captureperiod and adjusting so as to change the focal position of the opticalsystem in a second image capture period; displaying an image captured inthe first image capture period; generating a distribution of sharpnesscorresponding to focal positions based on an image captured in thesecond image capture period; and detecting the focal position of theoptical system, at which an image of a subject is in focus, based on thegenerated distribution of sharpness corresponding to the focalpositions.

A program stored in a recording medium according to an embodiment of thepresent invention includes: a focal position adjusting control step ofcontrolling an adjustment of a focal position of an optical system to apredetermined position in a first image capture period and an adjustmentto change the focal position of the optical system in a second imagecapture period; a display control step of controlling a displaying of animage captured in the first image capture period; a distributiongeneration control step of controlling a generation of a distribution ofsharpness corresponding to the focal positions based on the imagecaptured in the second image capture period; and a focused positiondetection control step of controlling a detection of a focal position ofthe optical system, at which an image of a subject is in focus, based onthe distribution of sharpness corresponding to the focal positionsgenerated by the process of the distribution generation control step.

A program according to an embodiment of the present invention instructsa computer to execute: a focal position adjusting control step ofcontrolling an adjustment of a focal position of an optical system to apredetermined position in a first image capture period and an adjustmentto change the focal position of the optical system in a second imagecapture period; a display control step of controlling a displaying of animage captured in the first image capture period; a distributiongeneration control step of controlling a generation of a distribution ofsharpness corresponding to the focal positions based on the imagecaptured in the second image capture period; and a focused positiondetection control step of controlling a detection of a focal position ofthe optical system, at which an image of a subject is in focus, based onthe distribution of sharpness corresponding to the focal positionsgenerated by the process of the distribution generation control step.

In the image capturing apparatus, method and program according to theembodiments of the present invention, in the first image capture period,the focal position of the optical system is adjusted to thepredetermined position, and in the second image capture period, thefocal position of the optical system is adjusted to be changed. Further,the image captured in the first image capture period is displayed, andbased on the image captured in the second image capture period, thedistribution of sharpness corresponding to the focal positions isgenerated. Further, based on the distribution of sharpness based on thefocal positions, a focal position of the optical system in which theimage of a subject becomes in the focused state is detected.

The image capturing apparatus according to the embodiment of the presentinvention may be an independent apparatus or may be a block for carryingout an image capturing processing.

According to the embodiments of the present invention, it is possible todetect the focused position without making the display image illegibleor incomplete. Further, the embodiments of the present invention makesit easy to properly set a focused position for any arbitrary subject.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the presentinvention will become more apparent from the following description ofthe presently exemplary embodiment of the invention taken in conjunctionwith the accompanying drawings, in which:

FIG. 1 is a block diagram showing a configuration of a digital videocamera to which an embodiment of the present invention is applied;

FIG. 2 is a flowchart explaining a capturing process;

FIG. 3 is a flowchart explaining an initializing process in theflowchart in FIG. 2;

FIG. 4 is a view explaining a change in a position of a focus lens inthe initializing process;

FIG. 5 is a view explaining a sharpness distribution;

FIG. 6 is a flowchart explaining a multi-point focused positiondetecting process in the flowchart in FIG. 2;

FIG. 7 is a view explaining a change in a position of a focus lens inthe multi-point focused position detecting process;

FIG. 8 is a view explaining a sharpness distribution;

FIG. 9 is a view showing an image example displayed on a display in FIG.1;

FIG. 10 is a view showing an image example displayed on the display inFIG. 1;

FIG. 11 is a view explaining a sharpness distribution;

FIG. 12 is a view explaining an adjusting method of an exposure time ofa CCD image sensor in association with a movement speed of a focus lens;

FIG. 13 is a view explaining an adjusting method of the exposure time ofthe CCD image sensor in association with the movement speed of the focuslens; and

FIG. 14 is a block diagram showing a configuration of a general purposepersonal computer.

DETAILED DESCRIPTION OF EMBODIMENTS

An image capturing apparatus according to an embodiment of the presentinvention includes: focal position adjusting means (for example, adriver controller 26 of FIG. 1) for adjusting a focal position of anoptical system in a first image capture period to a predeterminedposition and adjusting so as to change the focal position of the opticalsystem in a second image capture period; displaying means (for example,a display 22 for displaying an image provided in the condition where aswitching unit 24 of FIG. 1 connects a switch 23 to a terminal 23 a forthe first image capture period) for displaying an image captured in thefirst image capture period; distribution generating means (for example,a sharpness distribution generator 18 of FIG. 1) for generating adistribution of sharpness based on the focal positions in accordancewith the image captured in the second image capture period; and focusedposition detecting means (for example, a focused position detector 19 ofFIG. 1) for detecting the focal position of the optical system in whichan image of a target subject becomes in a focused state, based on thedistribution of sharpness based on the positions of the focusesgenerated by the distribution generating means.

The image capturing apparatus according to the present embodiment mayfurther include focused position display image generating means (forexample, a focused position display image generator 20 of FIG. 1) forgenerating a focused position display image that indicates focusedpositions detected by the focused position detecting means.

The image capturing apparatus according to the present embodiment mayfurther include image composing means (for example, a composing unit 21of FIG. 1) for combining the focused position display image generated bythe focused position display image generating means and the imagecaptured in the first image capture period. Further, the display may bearranged so as to display the composite image obtained by combining theimage captured in the first image capture period and the focusedposition display image.

The image capturing apparatus according to the present embodiment mayfurther include selecting means (for example, an operating unit 25 ofFIG. 1) for selecting a focused position from the focused positiondisplay image generated by the focused position display image generatingmeans. The focal position adjusting means may be arranged so as toadjust the focal position used in the first image capture period to afocal position corresponding to the focused position selected by theselecting means.

The image capturing apparatus according to the present embodiment mayfurther include zoom setting means (for example, the driver controller26 of FIG. 1) for controlling zoom operation of the optical system. Thefocal position adjusting means may be arranged so as to adjust the focalposition of the capturing optical system to a predetermined position inresponse to the zoom status set by the zoom setting means in the firstimage capture period, and recalculate the focused position of theoptical system obtained in the second image capture period in responseto the zoom status set by the zoom setting means.

An image capturing method according to an embodiment of the presentinvention includes the steps of: adjusting a focal position of anoptical system captured in a first image capture period to apredetermined position and adjusting so as to change the focal positionof the optical system captured in a second image capture period(processes at steps S55, S56 in a flowchart of FIG. 6); displaying theimage captured in the first image capture period (a process at a stepS63 in the flowchart of FIG. 6); generating a distribution of sharpnessbased on the focal positions based on the image captured in the secondimage capture period (a process at a step S60 in the flowchart of FIG.6); and detecting the focal position of the optical system in which animage of a subject becomes in a focused state based on the distributionof sharpness based on the focal positions generated (a process at a stepS61 in the flowchart of FIG. 6).

Similar mapping relationships hold for a recording medium and a programaccording to embodiments of the present invention as that of the imagecapturing method. Accordingly, their corresponding descriptions areomitted for the purpose of simplifying the description.

A digital video camera 1 according to an embodiment of the presentinvention will be described below with reference to the accompanyingdrawings.

A fixed lens 11 collects lights that forms an image of an imaging fieldand guides them to a zooming lens 12 to transmit therethrough. Thezooming lens 12 is controlled to move by an actuator 28 in the right andleft directions in the drawing, and by adjusting the image light ofimaging field depending on its position, an image of the imaging fieldis enlarged or reduced, and passed through a field lens 13 disposed atthe following stage.

The field lens 13 is a fixed lens and guides the image light of animaging field, whose zoom size is adjusted by the zooming lens 12, to afocus lens 14. An operation of the focus lens 14 is controlled by anactuator 29. The movement to the right or left direction in the figurechanges the focal position of the image light of imaging field. Thefocus lens 14 guides an image to be formed to a CCD image sensor 15.

In the present specification, the focal position is a position at whichan image of a subject located at an infinitely remote position is formedby an optical system block (the block may include the fixed lens 11, thezooming lens 12, the field lens 13 and the focus lens 14). Further, theoperation for changing the focal position is equivalent to an operationto change a distance from the optical block to the subject whose imageis formed on the CCD image sensor 15.

In other words, for the same optical zoom magnification, if a distancefrom the focal position to the CCD image sensor 15 is larger, a subjectin the image existing at a relatively closer position from the opticalblock would be in focus, and if the distance from the focal position tothe CCD image sensor 15 is smaller, a subject in the image existing at arelatively far position from the optical block would be in focus.

Regularly, in the case of capturing an image of a subject, it isobviously difficult to change the distance from the optical block to thesubject. Accordingly, the subject is brought into focus by adjusting theoptical block to change the focal position of the optical block. Here,the focal position is changed by changing the positions of the zoominglens 12 and focus lens 14 in the optical block.

Further, a focal position of the optical system at which an image of asubject formed by the optical block becomes in the focused state (or afocal position of the optical system at which a subject is in-focus) isreferred to as a focused position in the present specification.Accordingly, if a plurality of subjects exist in the imaging field atdifferent distances from the optical block, a plurality of potentialfocused positions exist, which respectively correspond to individualpositions of the subjects. The focused positions correspond to distancesto the subjects when they are viewed from the optical block.

For example, if there are a subject positioned at a remote location anda subject positioned at a closer location in the same image when theyare viewed from the optical block and if the position of the focus lens14 is changed sequentially in such a way that the focal position viewedfrom the CCD image sensor 15 is changed from a remote position to acloser position, the closer subject becomes in the focused state firstat a certain position (referred to as a first focused position), andthen the remote subject becomes in the focused state at another position(referred to as a second focused position).

The CCD (Charge Coupled Device) 15 photo-electrically converts lightpassed through the focus lens 14 into voltage values at respective pixelunits, and thereby generating an image signal to supply to a sharpnessdetector 17, a RAM 16 and a terminal 23 a of a switch 23.

The sharpness detector 17 determines the sharpness of an image based onthe image signal sent from the CCD image sensor 15, subsequentlydetermines an evaluation value based on the sharpness, and sends thesharpness and evaluation values to the sharpness distribution generator18. More specifically, for example, the sharpness detector 17, afterperforming a sharpness improving process such as a Laplacian filteringand the like on the image sent from the CCD image sensor 15, determinesthe number of pixels constituting an edge of the image having apredetermined pixel value or more, and sends the number of pixels as anevaluation value of the sharpness to the sharpness distributiongenerator 18. In the present invention, the filter used in the sharpnessimproving process is not limited to only the Laplacian filtering, andanother filtering having the similar function may be employed. Further,the evaluation value of sharpness is not limited to the value determinedby the foregoing manner, and other types of values determined bydifferent methods may also be employed. For example, magnitudes ofcontrasts between pixels may be used as the evaluation value ofsharpness.

The sharpness distribution generator 18 generates a distribution ofsharpness with respect to positions of the focus lens 14 based on:information regarding current positions of the focus lens 14 providedthrough a controller and driver 27 from a position sensor 31;information regarding current position of the zooming lens 12 providedfrom a position sensor 30; and the evaluation value of sharpnessprovided from the sharpness detector 17. Further, the sharpnessdistribution generator 18 sends the generated sharpness distribution tothe focused position detector 19.

The focused position detector 19 detects focus lens positionscorresponding to focused positions based on the sharpness distribution,and sends the focus lens positions to the focused position display imagegenerator 20. The sharpness distribution is prepared such that thevertical axis indicates the position of the focus lens 14 and thehorizontal axis indicates the evaluation value of sharpness.Accordingly, the focused position detector 19 enables to detectpositions of the focus lens 14 where sharpness of the sharpnessdistribution has a local maximum value or at an inflection point, as thefocus lens positions corresponding to the focused positions. In otherwords, at the position of the focus lens 14 where the sharpness of thesharpness distribution has a local maximum value or an inflection point,the sharpness is high (or in the focused state), thereby indicating thata captured image is regarded as in focus (an image of a subject becomesin focus). Further, the position of the focus lens 14 at that time isdetected as the focus lens position corresponding to the focusedposition.

The focused position display image generator 20 generates an image thatallows a user to visually recognize the focused positions, and sends thegenerated image to the composing unit 21.

The composing unit 21 combines the focused position display image sentfrom the focused position display image generator 20 and the imagesignal sent from the CCD image sensor 15 by superimposing these images,and displays on the display 22, which may be a CRD (Cathode Ray Tube),LCD (Liquid Crystal Display), a plasma display panel (PDP), an organiclight emission diode (OLED), a thin film electro-luminescence display(TFEL), a field emission display (FED) or the like.

The RAM 16 temporarily stores data corresponding to one field of theimage signal sent from the CCD image sensor 15, delays by a timingcorresponding to the one field and sends to a terminal 23 b.

The switching unit 24 switches the switch 23 to the terminal 23 a or 23b based on a signal sent by the driver controller 26 for identifyingwhether the image currently being captured, belongs to an even-numberedfield or odd-numbered field. In other words, the switching unit 24connects the switch 23 to the terminal 23 a in the case of theeven-numbered field, and connects to the terminal 23 b in the case ofthe odd-numbered field. Here, as mentioned above, the RAM 16 delays fora time period corresponding to the one field the image datacorresponding to the one field, and sends to the terminal 23 b.Accordingly, if the CCD image sensor 15 sends the even-numbered field,the switch 23 sends the image of the even-numbered field from theterminal 23 a to the composing unit 21, and the image of theeven-numbered field is stored in the RAM 16 at the same timing. If theCCD image sensor 15 sends the odd-numbered field in the followingtiming, the even-numbered field of the immediate preceding field, whichis stored in the RAM 16, is sent from the switch 23 to the composingunit 21 since the switch 23 is connected to the terminal 23 b, therebyrepeating these processes.

As a result, only the image of the even-numbered field is sent from theswitch 23 to the composing unit 21.

The operating unit 25 may include a switch, a button and/or the like,which are operated when a user sends instructions regarding the focalposition, the zoom or the like to the digital video camera 1. Anoperation signal in response to the operation instruction is sent to thedriver controller 26. The operating unit 25 may be configured as aso-called touch panel. The touch panel may be integrated with thedisplay 22.

The driver controller 26 sends a signal for controlling operations ofthe zooming lens 12 and focus lens 14, which correspond to the operationsignals from the operating unit 25, to the controller and driver 27while using position information of the zooming lens 12 and focus lens14 which is fed back from the controller and driver 27. Further, thedriver controller 26 sends a signal for indicating if the fieldcurrently captured by the CCD image sensor 15 is the even-numbered fieldor odd-numbered field, to the switching unit 24. Further, the drivercontroller 26 causes to operate the focus lens 14 in such a way that adistance from the optical block to a subject where an image becomes inthe focused state is varied from the intermittently nearest position toa intermittently remote position, so as to detect the focused positionthat serves as a reference (hereafter, referred to as a referencefocused position). The driver controller 26 further causes to detect theposition of the focus lens 14 corresponding to the reference focusedposition. Moreover, after the detection of the reference focusedposition, the driver controller 26 controls the controller and driver27, sets the focus lens 14 to the position corresponding to thereference focused position for the even-numbered field, and varies theposition of the focus lens 14 step-wisely for the odd-numbered field.

The controller and driver 27, upon receiving a control signal from thedriver controller 26, calculates respective movement directions anddistances based on position information of the zooming lens 12 and focuslens 14, which is sent from the position sensors 30, 31, operates theactuators 28, 29 based on the calculation result, and then moves thezooming lens 12 and the focus lens 14 to the positions corresponding tothe control signal. Moreover, the controller and driver 27 feeds theposition information of the zooming lens 12 and focus lens 14 back tothe driver controller 26 and simultaneously sends to the sharpnessdistribution generator 18.

The capturing process of the digital video camera in FIG. 1 will bedescribed below with reference to the flowchart of FIG. 2.

At a step S1, an initializing process is executed.

Here, the initializing process is explained with reference to aflowchart of FIG. 3.

At a step S21, the driver controller 26 controls the controller anddriver 27 to set the zooming lens 12 to a default zoom position. Morespecifically, when the default zoom is single magnification, the drivercontroller 26 instructs the controller and driver 27 to move the zoominglens 12 to a position where the single magnification zoom can beattained. In response to this instruction, the controller and driver 27determines the direction and distance to the position where the singlemagnification zoom can be attained based on the position information ofthe zooming lens 12 sent from the position sensor 30, and operates theactuator 28 to move the zooming lens 12 with the corresponding movementdirection and distance.

At a step S22, the driver controller 26 sets a counter L to Lmin, andcontrols the controller and driver 27 to set a position L of the focuslens 14 to a position where the image becomes in the focused state andthe distance from the optical block to the subject is the shortest,namely, set the focal position of the optical system to the positioncorresponding to the counter L=Lmin. More specifically, the drivercontroller 26 instructs the controller and driver 27 to move the focuslens 14 to the position Lmin where the focal position is the most remoteposition from the CCD image sensor 15 within a scanning range for theposition of the zooming lens 12. In response to this instruction, thecontroller and driver 27 determines the direction and distance to theLmin based on the position information of the focus lens 14 sent by theposition sensor 31, and operates the actuator 29 to move the focus lens14 by the corresponding movement direction and distance. In thefollowing description, the similar processes are used for moving thezooming lens 12 and focus lens 14. Accordingly, descriptions of theoperations of the controller and driver 27, actuators 28, 29 andposition sensors 30, 31 are omitted for the sake of simplification.

At a step S23, the driver controller 26 controls the switching unit 24to connect the switch 23 to the terminal 23 a.

At a step S24, the CCD image sensor 15 captures the image formed fromlight transmitted through the fixed lens 11, the zooming lens 12, thefield lens 13 and the focus lens 14, and sends as an image signal to thesharpness detector 17, the RAM 16 and the terminal 23 a of the switch23. Now, since the switch 23 is connected to the terminal 23 a, thisprocess causes to send the captured image to the composing unit 21.

At a step S25, the sharpness detector 17 detects the sharpness of theimage sent by the CCD image sensor 15. In other words, the sharpnessdetector 17, for examples, performs the Laplacian filtering on the imagesignal to improve the sharpness, and then sends the number of the pixelswhere the pixel value is a predetermined value or more, namely, thenumber of the pixels having a high possibility of forming the edge, asthe evaluation value of sharpness to the sharpness distributiongenerator 18.

At a step S26, the sharpness distribution generator 18 generates asharpness distribution based on information regarding the position ofthe focus lens 14 sent by the position sensor 31 and the sharpness datasent by the sharpness detector 17, and sends the generated sharpnessdistribution to the focused position detector 19. The sharpnessdistribution is a distribution represented in a form such that thehorizontal axis indicates the position of the focus lens and thevertical axis indicates the sharpness, and formed by accumulating theposition information of the focus lens and the information of thesharpness, which are repeatedly sent.

At a step S27, the focused position detector 19 judges whether or notany focused position is detected based on the sharpness distributionsent by the sharpness distribution generator 18. More specifically, thefocused position detector 19 detects the position of the focus lenscorresponding to the focused position based on the sharpnessdistribution and based on a judgment of whether or not any local maximumpoint or inflection point of the sharpness of the image is detected. Atthe step S27, if the focused position is not detected, the drivercontroller 26 carries out an increment of the counter L by apredetermined interval d at a step S28.

At a step S29, the driver controller 26 judges whether or not thecounter L is greater than a maximum value Lmax. If the counter L isjudged not to be greater, the process proceeds to a step S30, andcontrols the controller and driver 27 to set the position of the focuslens 14 to the position L, and the process returns to the step S24.

If the focused position is detected at a step S27, at a step S32, thedriver controller 26 sets a value L−d corresponding to the detectedfocused state in which d is subtracted from the counter L, as a focuslens position Lb corresponding to the reference focused position, andalso sets the focus lens 14 to a position corresponding to the counterL=Lb. In other words, the local maximum point or inflection point of thesharpness cannot be detected unless the focus lens 14 is located at aposition where the actual sharpness exceeds the local maximum point orinflection point. Thus, the position (L−d) returned by the distance dfrom the position of the focus lens 14 where the local maximum point orinflection point of the sharpness is detected is set as the positionwhere it becomes in the focused state.

At a step S33, the composing unit 21 displays the captured image sent bythe switch 23 on the display 22. In other words, in the initializingprocess, the focused position display image is not generated since thefocused position display image generator 20 has not been generated.Thus, the composing unit 21 displays the image sent by the switch 23 inits original state on the display 22.

At a step S29, if the counter L is judged to be greater than the Lmax,at a step S31, the focused position detector 19 judges if tendency ofchange in the generated sharpness distribution is monotonous increase ormonotonous decrease. If the change tendency is the monotonous increase,it sets Lmax+d for the counter L, and if the change tendency is themonotonous decrease, it sets Lmin+d for the counter L. Next, the processproceeds to a step S32.

In other words, the repetition of the processes at the steps S24 to 30causes the position of the focus lens 14 to be moved from L0 as Lmin topositions L1 to L5 (Lmax is L5) with the interval distance of d. In FIG.4, the vertical axis indicates the position of the focus lens 14, andthe scanning range (the positions from L0 to L5) is set depending on theposition of the zooming lens. Further, the horizontal axis indicates thetime. In the present example, in a period from a time t0 to a time t1, afirst field is captured. In a period from the time t1 to a time t2, asecond field is captured. In a period from the time t2 to a time t3, athird field is captured. In a period from the time t3 to a time t4, afourth field is captured. In a period from the time t4 to a time t5, afifth field is captured. Further, in a period from the time t5 to a timet6, a sixth field is captured.

In other words, as shown in FIG. 4, in the times t0 to t1 where thefirst field is captured, the focus lens 14 is set to the positioncorresponding to the counter L0. In the times t1 to t2 where the secondfield is captured, the focus lens 14 is set to the positioncorresponding to the counter L1. Moreover, in the times t2 to t3 wherethe third field is captured, the focus lens 14 is set to the positioncorresponding to the counter L2. Further, in the times t3 to t4 wherethe fourth field is captured, the focus lens 14 is set to the positioncorresponding to the counter L3. Moreover, in the times t4 to t5 wherethe fifth field is captured, the focus lens 14 is set to the positioncorresponding to the counter L4. Further, in the times t5 to t6 wherethe sixth field is captured, the focus lens 14 is set to the positioncorresponding to the counter L5. In other words, in FIG. 4, the positionof the focus lens 14 is changed at the six steps in the right or leftdirection in FIG. 1. For example, when the leftmost position in FIG. 1corresponds to the position L0 of FIG. 4, the focus lens 14 is moved atthe six steps to the right direction at the interval distance of d, andthe focal position is changed accordingly.

Furthermore, with the process at the step S25, the sharpnessdistribution generator 18 detects the sharpness for each position offocus lens 14, and generates the sharpness distribution, for example, asshown in FIG. 5. In FIG. 5, the vertical axis indicates the sharpness,and the horizontal axis indicates the position of the focus lens 14. InFIG. 5, when the position of the focus lens 14 is the position L2, thesharpness indicates an local maximum value p. Thus, when the counterL=L3, at the step S27, the focused state is detected. Thus, for example,on and after the counter L4, the processes at the steps S24 to S30 arenot performed. Moreover, the focus lens 14 is set to the positioncorresponding to the counter L=L2, and the image captured in this stateis displayed on the display 22.

As a result, the focus lens 14 is set to the position Lb of the focuslens corresponding to the reference focused position. This means thatthe captured image is displayed, in which the nearest subject within acapture range is focused from the optical block.

The description returns to the flowchart in FIG. 2.

At the step S2, a multi-point focused position detecting process isexecuted.

Here, the multi-point focused position detecting process is explainedwith reference to a flowchart in FIG. 6.

At the step S51, the driver controller 26 sets the zooming lens 12 atthe set position. In other words, in the case of the first process, withthe process at the step S1, if the default is single magnification, thezooming lens 12 is set to the position corresponding to the singlemagnification zoom. In the case thereafter, the position of the zoominglens is set by the process at the step S7 which will be described later.

At the step S52, the driver controller 26 judges whether or not thefield of the image currently being captured is the even-numbered field.Here, the field number is assumed to be sequentially incremented, one byone, with the start number of 1. Thus, for example, in the firstprocess, since this field is the first field, it is judged that thefield is not the even-numbered field, and the process proceeds to a stepS53.

At the step S53, the driver controller 26 judges whether or not it isthe first process. For example, if it is the first process, thecontroller 26 sets the counter L to the minimum value Lmin at a stepS54. In other words, in the case of FIG. 4, if the focus lens 14 isconstructed to allow movement with the six steps from L0 to L5, theminimum value Lmin becomes the position L0.

At a step S55, the driver controller 26 sets the focus lens 14 to aposition corresponding to the counter L.

At a step S56, the driver controller 26 controls the switching unit 24to connect the switch 23 to the terminal 23 b.

At a step S57, the CCD image sensor 15 captures an image formed fromlight transmitted through the fixed lens 11, the zooming lens 12, thefield lens 13 and the focus lens 14, and sends as an image signal to thesharpness detector 17, the RAM 16 and the terminal 23 a of the switch23.

At a step S58, the RAM 16 sends an image of the field capturedimmediately before, through the terminal 23 b and the switch 23, to thecomposing unit 21. In other words, the image, which is not captured bythe CCD image sensor 15 and is stored in the RAM 16, is sent to thecomposing unit 21.

At a step S59, with similar way as in the process at the step S25 of theflowchart in FIG. 3, the sharpness detector 17 calculates the sharpnessfrom the image sent by the CCD image sensor 15 and sends the sharpnessto the sharpness distribution generator 18.

At a step S60, with similar way as in the process at the step S26 of theflowchart in FIG. 3, the sharpness distribution generator 18 generatesthe sharpness distribution based on information regarding the positionof the focus lens 14 sent by the position sensor 31 and the sharpnesssent by the sharpness detector 17, and sends to the focused positiondetector 19.

At a step S61, with similar way as in the process in which the presenceor absence of the focused position is judged in the process at the stepS26 of the flowchart in FIG. 3, the focused position detector 19 detectsthe focused position from the sharpness distribution sent by thesharpness detector 17, and sends to the focused position display imagegenerator 20. In this process, there may be a case such that no focusedposition is detected. In such a case, information indicating that nofocused position is detected is sent.

At a step S62, the focused position display image generator 20 generatesa focused position display image based on the information of the focusedposition sent by the focused position detector 19, and stores in abuilt-in memory (not shown in the figure).

At a step S63, the composing unit 21 combines the focused positiondisplay image stored in the built-in memory (not shown in the figure) ofthe focused position display image generator 20 and the image of theimmediate preceding field sent from the RAM 16 by superimposing theseimages, and displays the combined image on the display 22.

On the other hand, at the step S53, if it is judged that the process isnot the first process, at a step S64, the driver controller 26increments the counter L by d. At a step S65, the driver controller 26judges whether or not the counter L is greater than the maximum valueLmax. If it is greater, the process proceeds to a step S54. If it isjudged not to be greater, the process proceeds to a step S55.

In other words, at a step S64, if the counter L prior to the process isL1 as shown in FIG. 4, the counter L is incremented by d and becomes L2.As a result, at the step S55, the focus lens 14 is set to thecorresponding position. Further, if the counter L prior to the processis L5 as shown in FIG. 4, the counter L is incremented by d and exceedsthe maximum value L5. As a result, the counter L is returned to theminimum value at the step S54.

Further, at the step S52, if it is the even-numbered field, the processproceeds to a step S66. The driver controller 26 sets the position ofthe focus lens 14 to the position Lb corresponding to the referencefocused position determined by the process at the step S1.

At a step S57, the driver controller 26 connects the switch 23 to theterminal 23 a. At a step S68, the CCD image sensor 15 captures an imageformed from light transmitted through the fixed lens 11, the zoominglens 12, the field lens 13 and the focus lens 14 and sends as an imagesignal to the sharpness detector 17, the RAM 16 and the terminal 23 a ofthe switch 23.

At a step S69, the RAM 16 stores the image sent by the CCD image sensor15, and the process proceeds to the step S63.

The repetition of the foregoing processes causes the focus lens 14 to beoperated as shown in FIG. 7. In FIG. 7, in similar way as in FIG. 4, thevertical axis indicates the position of the focus lens 14, and thehorizontal axis indicates the time. In an example of FIG. 7, theposition Lb of the focus lens 14 corresponding to the reference focusedposition is assumed to be L2. Alternatively, a position other than theabove may also be used as the position of the focus lens 14corresponding to the reference focused position.

In other words, at the times t10 to t11, for the image captured by theCCD image sensor 15, the first field is the odd-numbered field and thefirst process is prosecuted. Thus, with the process at the step S54, thecounter L is set for Lmin=L0, and the focus lens 14 is set at thecorresponding position. In the next timing at the times t11 to t12, forthe image captured by the CCD image sensor 15, the second field is theeven-numbered field. Hence, the focus lens 14 is set to the position Lb(≅L2) of the focus lens 14 corresponding to the reference focusedposition.

Moreover, at the times t12 to t13, for the image captured by the CCDimage sensor 15, the third field is the odd-numbered field and not thefirst process. Thus, at a step S64, the counter L is incremented by dand set to L1. Hence, the focus lens 14 is moved from the position L0 tothe position L1.

Next, at the times t13 to t14 of the next timing, for the image capturedby the CCD image sensor 15, the fourth field is the even-numbered field.Thus, the focus lens 14 is set to the position Lb (≅L2) of the focuslens 14 corresponding to the reference focused position.

Similarly, at the times t14 to t15, for the image captured by the CCDimage sensor 15, the fifth field is the odd-numbered field and not thefirst process. Thus, at the step S64, the counter L is incremented by dand set to L2. Hence, the focus lens 14 is moved from the position L1 tothe position L2.

Hereafter, at the times t15 to t16, t17 to t18, t19 to t20, and t21 tot22, for the images captured by the CCD image sensor 15, the sixth,eighth, tenth and twelfth fields are the even-numbered fields. Thus, thefocus lens 14 is set for the position Lb of the focus lens 14corresponding to the reference focused position.

Further, at the times t16 to t17, t18 to t19 and t20 to t21, for theimages captured by the CCD image sensor 15, the seventh, ninth andeleventh fields are the odd-numbered fields and not the first process.Thus, at the step S64, the counter L is sequentially incremented by dand sequentially set for L=L3, L4 and L5. Consequently, at the timingsof the respective t16, t18 and t20, the focus lens 14 is moved and setfrom the position Lb to the position L3, from the position Lb to theposition L4, and from the position Lb to the position L5, respectively.

Next, at the times t22 to t23, the thirteenth field is the odd-numberedfield and not the first process. Thus, at the step S64, the counter L issequentially incremented by d and set to the counter L=L5+d. However, itis judged to be the maximum value Lmax or more at the step S65 and thecounter L is set to Lmin=L0 at the step S54. As a result, the focus lens14 is moved from the position L2 to the position L0. Hereafter, thesimilar processes are repeated.

With the foregoing processes, when a field of the even-numbered field iscaptured, the focus lens 14 is moved to the position Lb of the focuslens 14 corresponding to the reference focused position as indicated bya thick hatching line in FIG. 7. When a field of the odd-numbered fieldis captured, as indicated by a thin solid line in FIG. 7, the positionof the focus lens 14 is varied gradually. As a result, when the field ofthe even-numbered field is captured with the process at the step S67,the switch 23 is connected to the terminal 23 a. When the focus lens 14is set to the position of the focus lens 14 corresponding to thereference focused position, the image sent by the CCD image sensor 15 issent to the composing unit 21. When the field of the odd-numbered fieldis captured with the process at the step S56, the switch 23 is connectedto the terminal 23 b, and the image of the imaging field immediatelybefore (=the even-numbered field), which is captured in the state wherethe focus lens 14 is set to the position of the focus lens 14corresponding to the reference focused position and stored in the RAM16, is sent to the composing unit 21. Accordingly, although the focuslens 14 is moved by the one field unit, the display 22 displays thereononly the image of the even-numbered field which is captured in the statewhere the focus lens 14 is set to the position Lb corresponding to thereference focused position. Thus, only the focused image is displayed.Accordingly, it is possible to prevent from displaying images which maybe obtained during a period of moving the focus lens 14 for detection ofthe focused position and may not be in focus.

On the other hand, at the timing of the odd-numbered field, theprocesses at the steps S59 to S60 are repeated based on the imagescaptured at the sequentially different positions of the focus lens 14.For example, the sharpness distribution shown in FIG. 8 is generated,and the focused position is determined based on this sharpnessdistribution at the step S61. In FIG. 8, the vertical axis indicates theevaluation value indicating the sharpness, and the horizontal axisindicates the position of the focus lens. For example, when thesharpness distribution is obtained as shown in FIG. 8, the local maximumvalue or maximum value is obtained at positions Ln, Lf of the focus lensin FIG. 8. Thus, the positions Ln, Lf are selected as the focusedpositions.

Moreover, an image such as one shown in FIG. 9, for example, isdisplayed on the display 22 by generating the focused position displayimage with the process at the step S62 and combining the generated imagewith the captured image by superimposing with the process at the stepS63. Here, an image 51 of FIG. 9 is an image of a wire net fence locatedin the front and a basket ball goal in the back is captured. Moreover,in FIG. 9, the focused position display image, on which the capturedimage is superimposed, is displayed with an arrow straight line 61 whichare drawn in the right and left direction at the lower portion and arenoted as “Near” at the left end and as “Far” at the right end,respectively and with columns 62, 63 indicating the focused positions.

The straight line 61 is a scale indicating the position of the zoominglens 14 (or serves as a scale indicating the focused position). Each ofthe columns 62, 63 indicates the focused position. For example, if thesharpness distribution is indicated as shown in FIG. 8, the column 62corresponds to the position Ln, and the column 63 corresponds to theposition Lf, respectively. Further, the length in the vertical directionin FIG. 8 of each column represents the magnitude of the evaluationvalue. Moreover, the columns 62, 63 may be selected by using apredetermined pointer or the like with the operating unit 25.

Accordingly, by displaying the focused position display imagesuperimposed on the captured image on the display 22, a user may be ableto recognize a plurality of the focused positions in an image of thecurrent imaging field only by viewing the displayed image depending onthe position of the focus lens 14. The focused position, which is aposition of a subject that can be focused, is adjusted by the focus lens14, and the focal distance of the entire optical system is adjusted bythe zooming lens.

The description returns to the flowchart of FIG. 2.

At the step S3, the driver controller 26 judges whether or not thefocused position is changed. In other words, for example, if the image51 as shown in FIG. 9 is displayed on the display, the driver controller26 judges whether or not the operating unit 25 is operated and a columnindicating the focused position which is not the column corresponding tothe current reference focused position is selected. If the currentreference focused position is the focused position corresponding to thecolumn 62 (in the case of Lb=Ln) and if the column 63 is selected, thefocused position is judged to be changed, and the process proceeds tothe step S4.

At the step S4, the driver controller 26 moves the focus lens 14 to theposition Lf corresponding to the new (selected) focused position, and atthe step S5, sets the moved position as the position Lb of the focuslens 14 corresponding to the reference focused position. The processreturns to the step S2.

In other words, with the process at the step S4, the focus lens 14 ismoved to the position Lf indicated in the sharpness distribution shownin FIG. 8. The image in which the subject existing on the deeper side isbrought into focus, for example, as shown in FIG. 10, is displayed.Here, an image 71 of FIG. 10 becomes the image in which the basket goalexisting in the back side of the fence is brought into focus, and thefront fence is not in focus. Further, with the process at the step S5,the position Lf of the focus lens 14 in which the basket goal in thisstate is in the focused state is set as the position Lb of the focuslens 14 corresponding to the reference focused position, and theprocesses on and after the step S2 are repeated.

With the above-mentioned processes, the user is allowed to view thefocused position display image displayed on the display 22 and select anarbitrary focused position from a plurality of the focused positions,and further switch and display the image for the selected focusedposition.

The explanation returns to the flowchart of FIG. 2.

If the focused position is not changed at the step S3, at the step S6,the driver controller 26 judges whether or not the operating unit 25 isoperated and the zoom is changed. If the zoom magnification is changed,at the step S7, the zooming lens 12 is operated on the basis of thechanged magnification, and data of the focused positions is changed(cleared) at the step S8. Next, the process returns to the step S2. Inother words, if the position of the zooming lens 12 is changed, thefocal distance of the optical system changes and the sharpnessdistribution also changes, which consequently disables the use of thedata of the focused positions until that time (more specifically, thesharpness distribution). Accordingly, the process at the step S8 changes(clears) the sharpness distribution that is the focused position datauntil that time, and the process at the step S2 redetects the focusedposition at the new position of the zooming lens 12 (newly determinesthe sharpness distribution). If the property of the zooming lens 12 isalready known, the new position of the zooming lens 12 may be calculatedand the data of the focused positions until that time (the sharpnessdistribution) may be changed. At this time, the data of the focusedpositions (the sharpness distribution) may be continuously held.

At the step S6, if the zoom is judged not to be changed, the drivercontroller 26 judges whether or not the end of the image capturing isinstructed at the step S9. If the end of the image capturing isinstructed, the process is ended. Further, at the step S9, if the end ofthe image capturing is not instructed, the process returns to the stepS2. The processes on and after this are repeated.

In other words, with the process at the step S1, at first, the imagecaptured in the situation such that the nearest subject in the capturerange is brought into focus from the optical block is displayed, and, inthat state, a plurality of focused positions are detected by the processat the step S2. At this time, for example, since the image 51 of FIG. 9is displayed on the display 22, the focused position display imageindicating the information of the focused positions is superimposed anddisplayed on the image at the initial stage. Thus, the distance of thefocused position, the number of the focused positions and the evaluationlevel of the sharpness at the focused position may be recognized on thebasis of the positions, number and sizes of the columns. Further, theselection of the column enables the position of the focus lens 14 to beswitched to the desirable focused position among the plurality offocused positions. Thus, for example, the selection of the column 63enables the displayed image to be switched from the image 51 of FIG. 9to the image 71 of FIG. 10, and enables the easy selection of the imageat any focused position.

As a result, in the present embodiment, only the selection of thefocused position within the displayed image is necessary for switchingthe focus point in order to display an image for an arbitrary subjectamong a plurality of subjects existed in the same field.

The foregoing description has been explained for the case such thatthere are two local maximum values or maximum values within thesharpness distribution and their corresponding positions are regarded asthe focused positions. However, in the sharpness distribution, not onlythe local maximum value or maximum value, but also an inflection pointmay be regarded as the focused position. In other words, if thesharpness distribution as shown in FIG. 11 is obtained, positions Lo, Lpand Lq may also be recognized as the focused positions, respectively.Typically, the focused position is the focal position where thesharpness of the image captured while the focal position is being variedhas the local maximum value or maximum value. However, if they aresuperimposed, namely, if a plurality of focused positions exist in thesame imaging field, there may be a case such that the local maximumvalues or maximum values are superimposed on each other. In such a case,a region having the maximum value or local maximum value may besuperimposed on an increasing region or decreasing region, therebycausing an inflection point therein. Accordingly, it may be consideredthat the local maximum value or maximum value exists in a vicinity ofthe inflection point. Alternatively, the infinitely remote position suchas the position Lr in FIG. 11 where the sharpness increases monotonouslymay be regarded as the focused position.

In the foregoing description, since the position of the focus lens 14 ischanged for each field, there may be possibility such that the movementof the focus lens 14 within the exposure period of the CCD image sensor15 is not completed.

As an example, as shown in FIG. 12, a case such that the focus lens 14is moved from the position Lb to Lx is considered below. In FIG. 12, theupper portion indicates a synchronization signal, the middle portionindicates the position of the focus lens 14, and the bottom portionindicates a clock for counting the exposure period of the CCD imagesensor 15. The middle portion of FIG. 12 indicates the position of thefocus lens 14 corresponding to the clock for counting the exposureperiod of the CCD image sensor 15 at the bottom portion.

As represented by a solid line in FIG. 12, in the present example, it isassumed that, at a clock C1 of the timing when the synchronizationsignal rises up, the focus lens 14 starts moving from the position Lb tothe position Lx. Further, at this time, if it is assumed that theexposure period of the CCD image sensor 15 is for the clocks C6 to C12,the focus lens 14 becomes the exposure state during the movement to theposition Lx in the period of the clocks C6 to C9. Thus, the CCD imagesensor 15 cannot accurately capture the image when the focus lens 14 isset to the position Lx. In this case, for example, as represented by adotted line in FIG. 12, the actuator 29 that can be operated at a highspeed and enables to complete of the movement of the focus lens 14 untilthe clock C6 may be used. However, there is possibility of increasing acost. Accordingly, in this case, as shown in FIG. 13, the exposureperiod may be reduced to the clocks C9 to C12 so as to enable to startthe image capturing after the completion of the movement to the positionLx of the focus lens 14. Hence, without increasing the cost of hardwaresuch as the actuator 29 and the like, it is possible to attain theaccurate image capturing in the situation where the focus lens 14 is setto the position Lx.

In the foregoing description, in the process at the step S1 in theflowchart of FIG. 2, the reference focused position is defined as thefocused position whose focal distance is for the most front location.However, the present invention is not limited thereto. Alternatively,the focused position may exist at the deepest location, or if thesharpness increases monotonously as mentioned above, the position of thefocus lens 14 at the infinitely remote distance may be defined as thereference position. Further, the order of changing the position of thefocus lens 14 may be changed, for example, not only from the positionsL0 to L5 in FIG. 4 but also from L5 to L0. Moreover, after the arrivalat the position L0 to L5, the order may be changed from L5 to L0 torestart from L0 to L5. This mechanism allows to reduce the maximumdistance of movement of the focus lens. Accordingly, it is possible tominimize the decrease of the exposure period as explained by referringto FIGS. 12, 13.

Further, in the above-mentioned description, the case has been explainedin which the counter L indicating the position of the focus lens 14 isincremented by the interval d and in association with this, the focuslens 14 is moved by the interval d. However, the present invention isnot limited to the case where the focus lens 14 is always moved at theinterval d of the equal amount. Alternatively, the counter L may bechanged by non-equal intervals, and the focus lens 14 may be moved bynon-equal intervals.

Moreover, in the above-mentioned description, as shown in FIG. 7, thecase has been explained in which the images of the even-numbered fieldare displayed on the display 22, and the images of the odd-numberedfield are used to determine the focused position. However, the presentinvention is not limited thereto. Alternatively, images of theodd-numbered field may be displayed on the display 22, and images of theeven-numbered field may be used to determine the focused position.Furthermore, images of every other fields may be displayed or used fordetermined the focused position. Further, images of fields having aninterval other than anything described above may also be displayed orused for determining the focused position.

Further, in the above-mentioned description, the example of using theCCD image sensor 15 as the device for capturing an image has beenexplained. Alternatively, a different image sensor may also be used. Forexample, instead of the CCD image sensor 15, a CMOS (Complementary MetalOxide Semiconductor) may be used. The similar effect may be achieved asin the case of the CCD image sensor 15.

According to the present invention, even if there are a plurality ofsubjects within an imaging field, which may serve as a plurality offocused positions, it is possible to detect the focused position withoutmaking the displayed image illegible, and to properly and easily set anarbitrary subject to the focused position.

Although the foregoing series of image capturing processes may beexecuted by hardware, they may also be executed by software. If theseries of the processes are executed by the software, programsconstituting the software are installed from a recording medium or mediato a computer assembled with dedicated hardware or a general purposepersonal computer or the like, which can perform various functions byinstalling various programs.

FIG. 14 shows a configuration example of a general purpose personalcomputer. A CPU (Central Processing Unit) 101 is built in this personalcomputer. An input output interface 105 is connected through a bus 104to the CPU 101. A ROM (Read Only Memory) 102 and a RAM (Random AccessMemory) 103 are connected to the bus 104.

An input unit 106 including input devices such as a keyboard, a mouthand the like for a user to input an operation command, an output unit107 for outputting an image of a processing operation screen or aprocessed result to a displaying device, a memory 108 including a harddisc drive for storing a program and various data and the like, and acommunicating unit 109, which may include a LAN (Local Area Network)adaptor and the like, for executing a communicating process through anetwork represented by the Internet are connected to the input outputinterface 105. Further, a drive 110 is connected for reading and writinga data from and to the recording media, such as a magnetic disc 121(including a flexible disc), an optical disc 122 (including CD-ROM(Compact Disc-Read Only Memory), DVD (Digital Versatile Disc), Blu-RayDisc and HD (High-definition)-DVD), a magneto-optical disc 123 (MD (MiniDisc), a semiconductor memory 124 and the like.

The CPU 101 executes the various processes based on a program stored inthe ROM 102, or a program which is read out from the magnetic disc 121,optical disc 122, magnet-optical disc 123 and semiconductor memory 124and installed into the memory 108 and loaded from the memory 108 to theRAM 103. The RAM 103 temporary stores data required for execution ofvarious processes by the CPU 101.

In this specification, at the steps of describing a program recorded ina recording medium, the processes may be carried out not only in timeseries along the order of mention but also executed not in the timeseries manner. Alternatively, the processes may also be executed inparallel or individually.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

1. An image capturing apparatus comprising: focal position adjustingmeans for adjusting a focal position of an optical system to apredetermined position in a first image capture period and adjusting soas to change the focal position of the optical system in a second imagecapture period; displaying means for displaying an image captured in thefirst image capture period; distribution generating means for generatinga distribution of sharpness corresponding to focal positions based on animage captured in the second image capture period; and focused positiondetecting means for detecting the focal position of the optical system,at which an image of a subject is in focus, based on distribution ofsharpness corresponding to focal positions generated by the distributiongenerating means.
 2. The image capturing apparatus according to claim 1,wherein: the first image capture period and the second image captureperiod are alternately repeated.
 3. The image capturing apparatusaccording to claim 1, wherein: the focal position adjusting meansadjusts the focal position of the optical system by moving the positionof a focus lens.
 4. The image capturing apparatus according to claim 1,wherein: the focal position adjusting means adjusts the focal positionof the optical system relative to an image capturing device by movingthe position of the image capture device.
 5. The image capturingapparatus according to claim 1, wherein: the focal position adjustingmeans adjust the focal position of the optical system relative to animage capturing device by changing a form of the optical system.
 6. Theimage capturing apparatus according to claim 3, wherein: in the secondimage capture period, the focal position adjusting means adjusts thefocal position by moving the position of the focus lens with non-equalintervals.
 7. The image capturing apparatus according to claim 1,further comprising: focused position display image generating means forgenerating a focused position display image that indicates focusedpositions detected by the focused position detecting means.
 8. The imagecapturing apparatus according to claim 7, further comprising: imagecomposing means for combining the focused position display imagegenerated by the focused position display image generating means and theimage captured in the first image capture period; wherein the displaymeans display the image captured in the first image capture period thatis combined with the focused position display image.
 9. The imagecapturing apparatus according to claim 1, further comprising: selectingmeans for selecting a focused position from the focused position displayimage generated by the focused position display image generating means;wherein the focal position adjusting means adjust the focal position ofthe image captured in the first image capture period to a focal positioncorresponding to the focused position selected by the selecting means.10. The image capturing apparatus according to claim 1, furthercomprising: zoom setting means for controlling zoom operation of theoptical system; wherein the focal position adjusting means adjusts thefocal position of the optical system to a predetermined position inresponse to the zoom status set by the zoom setting means in the firstimage capture period, and recalculates the focused position of theoptical system obtained in the second image capture period in responseto the zoom status set by the zoom setting means.
 11. The imagecapturing apparatus according to claim 1, further comprising: zoomsetting means for controlling zoom operation of the optical system;wherein the focal position adjusting means adjusts the focal position ofthe optical system to a predetermined position in response to the zoomstatus set by the zoom setting means in the first image capture period,and adjusts a range in which the focal position of the optical system isvaried in response to the zoom status set by the zoom setting means inthe second image capture period.
 12. An image capturing methodcomprising the steps of: adjusting a focal position of an optical systemto a predetermined position in a first image capture period andadjusting so as to change the focal position of the optical system in asecond image capture period; displaying an image captured in the firstimage capture period; generating a distribution of sharpnesscorresponding to focal positions based on an image captured in thesecond image capture period; and detecting the focal position of theoptical system, at which an image of a subject is in focus, based on thegenerated distribution of sharpness corresponding to focal positions.13. A recording medium storing a computer readable program, the programcomprising: a focal position adjusting control step of controlling anadjustment of a focal position of an optical system to a predeterminedposition in a first image capture period and an adjustment to change thefocal position of the optical system in a second image capture period; adisplay control step of controlling a displaying of an image captured inthe first image capture period; a distribution generation control stepof controlling a generation of a distribution of sharpness correspondingto the focal positions based on the image captured in the second imagecapture period; and a focused position detection control step ofcontrolling a detection of the focal position of the optical system, atwhich an image of a subject is in focus, based on the distribution ofsharpness corresponding to focal positions generated by the process ofthe distribution generation control step.
 14. A program embodied in acomputer-readable medium to control a processor to implement a methodcomprising: a focal position adjusting control step of controlling anadjustment of a focal position of an optical system to a predeterminedposition in a first image capture period and an adjustment to change thefocal position of the optical system in a second image capture period; adisplay control step of controlling a displaying of an image captured inthe first image capture period; a distribution generation control stepof controlling a generation of a distribution of sharpness correspondingto the focal positions based on the image captured in the second imagecapture period; and a focused position detection control step ofcontrolling a detection of the focal position of the optical system, atwhich an image of a subject is in focus, based on the distribution ofsharpness corresponding to focal positions generated by the process ofthe distribution generation control step.
 15. An image capturingapparatus comprising: a focal position adjusting device operable toadjust a focal position of an optical system to a predetermined positionin a first image capture period and change the focal position of theoptical system in a second image capture period; a display operable todisplay an image captured in the first image capture period; adistribution generator operable to generate a distribution of sharpnesscorresponding to focal positions based on an image captured in thesecond image capture period; and a focused position detector operable todetect the focal position of the optical system, at which an image of asubject is in focus, based on the generated distribution of sharpness.